One method of repairing a damaged sewer pipe is known as cured-in-place pipelining (CIPP). CIPP involves using a lining assembly including a main bladder, a lateral bladder tube extending from the main bladder, and a lateral liner tube. The lateral bladder tube may be separate from the main bladder to accommodate instances when a different diameter of lateral pipe needs repaired. Such a liner assembly and a method of use are disclosed in U.S. Pat. No. 5,950,682, which is owned by the applicant and hereby incorporated by reference in its entirety (and attached as Appendix A).
However, problems exist with such methods and apparatus. Because the lateral bladder tube extends from the main bladder, the two bladders must be inflated at the same time in some embodiments. This increases the internal pressure on the connection between the main and lateral bladder. If the seal is not tight, a leak may form. The leak makes it difficult to fully inflate the bladders to press the lateral liner and liner collar against the wall of the lateral pipe and the junction between the main and lateral pipe. When this pressure is not great enough, the liner will not cure properly. There may be folds in the liner, or the liner may cure away from the wall of the pipe. If folds are formed, they would have to be cut or sanded out. If the liner cures away from the wall, it would have to be redone. In either case, it would be both expensive and time consuming to fix the problem of the liner assembly not inflating properly.
A separate problem exists with methods and apparatus that include independent main and lateral bladders. In those embodiments, the means of connecting the bladders to a launcher interferes with the process of installing a cured-in-place liner. Specifically, the lateral or auxiliary bladder disclosed in U.S. Pat. No. 5,950,682 is attached to the interior of a rim protruding from a launcher device. Such an attachment can create voids between the launcher device and the bladders, allowing resin to interact with the launcher device. This increases clean up time and potentially damages the launcher device. Therefore, there is a need in the art for an improved or alternative method and apparatus for repairing the junction of a main and lateral pipe that incorporates the use of a separate main and lateral bladder to expand to press a lateral liner tube and/or a main line liner member against the wall of a lateral pipe and the junction of a main and lateral pipe.
There is also a need in the art for a method and apparatus for repairing the junction of a main and lateral pipe that is easily changeable at a job site to account for varying diameters of pipes. A limitation of U.S. Pat. No. 5,950,682 is that the opening of the launcher device must be substantially the same diameter as the lateral bladder. This limitation may be unnecessary, due to the fact that many different diameters of lateral pipes may be used in sewer systems. Therefore, a separate launcher would be required to repair a sewer system having lateral pipes of varying diameters. It can be both expensive and time consuming to provide separate launchers to repair different pipes within the same sewer system.
Lastly, there is a need in the art for a method and apparatus for repairing the junction of a main and lateral pipe that includes a fully reusable lateral bladder. Known methods employ pushing a liner into a lateral bladder using a rod, which requires an end of the lateral bladder to be open, in order to string the liner along the lateral bladder. The open end of the bladder is then closed for the inversion process. The bladder may be discarded after the inversion and curing process. If an attempt to reuse the bladder was to be made, such a reuse can be impractical and inconvenient. Because the end of the lateral bladder must be open during placement of the liner, the lateral bladder must be cut after a first use to place a second liner within the lateral bladder. This must be done in order to gain access to the interior of the bladder. The cutting makes the lateral bladder shorter. After placing a second liner within the lateral bladder, the bladder must be reclosed, using even more bladder material to make the seal. For many applications, the loss of such a bladder length would make reuse of the bladder impractical, as the bladder is unfit for pipe repair lengths equal to or greater than the first pipe repair. Furthermore, the process of cutting the lateral bladder and reclosing it is a time intensive process. Therefore, there is a need in the art for an improved or alternative method and apparatus for repairing the junction of a main and lateral pipe that incorporates the use of a fully reusable lateral bladder that is configured for rapid reuse.